Abstract: The literature was reviewed regarding the sorption and transport of a nonionic organic pesticide aldicarb, an extremely toxic and relatively water soluble carbamate insecticide that has been detected in ground water across the United States. Leaching of organic compounds through the soil poses a serious threat to ground water. Sorption is a critical factor in determining how rapidly a pesticide will leach through the vadose zone. Aldicarb behaves as a nonionic organic compound being adsorbed primarily by soil organic matter and to a lesser extent by clay minerals. The assumption of a local equilibrium between the soil particles and the pore fluid is not always correct. Aldicarb transport may be controlled by nonequilibrium effects.